Chapter Two – page 1
AN INTEGRATIVE APPROACH TO PSYCHOPATHOLOGY
I. One-Dimensional versus Multidimensional Models
A. One-dimensional models posit single causes of psychopathology (e.g., its
all conditioning, its all biology, its all social or psychological).
B. Multi-dimensional models hold that a system of different reciprocal
influences (i.e., biological, cognitive, learning, emotional, social, cultural)
interact in complex ways to yield the major etiological and maintaining
processes responsible for abnormal behavior. As such, any biological or
environmental influence can become part of this system and cannot be
considered in an isolated context.
II. Genetic Contributions to Psychopathology
A. The nature of genes
1. Genes are segments of deoxyribonucleic acid (DNA) that contain
information about specific characteristics.
2. Each human cell contains 46 chromosomes (arranged in 23 pairs –
half from each parent).
3. The first 22 pairs of chromosomes program development of body
(including the brain) and the last pair, called the sex chromosomes,
determines sex phenotype.
4. Dominant gene is one of the pair of genes that determine a particular
trait and the effect can be quite noticeable.
5. Recessive gene must be paired with another recessive gene to
determine a trait.
6. Defective gene results if something is wrong with respect to the
ordering of DNA molecules on the double helix.
7. Genes seldom determine our physical development in any absolute
way and the same is true for psychopathology. Much of human
development and behavior is polygenic (i.e., influences by many
genes that individually exert a tiny effect). Because of this, scientists
look for patterns of influence across genes using a procedure called
B. New developments in the study of genes and behavior
1. The best estimate for genetic contribution to enduring personality
traits and cognitive abilities in humans is about 50%.
2. With respect to psychological disorders, genetic influences seem to
account for less than half the etiological explanation; however, no
individual genes have been identified relating to any major
3. More important questions now are how genetic and environmental
factors interact to influence psychological disorders. Chapter Two – page 2
C. The interaction of genetic and environmental effects
1. An example of gene-environment interaction was proposed by Eric
Kandel, who stated that the process of learning may change the
genetic structure of cells. This may occur when environmental
processes turn on dormant genes and changes in the brain's
biochemical functioning. This view lends support to the notion that we
are less hardwired than previously thought.
2. The diathesis-stress model
a. According to this model of gene-environment interaction,
persons inherit from multiple genes tendencies to express
certain traits or behaviors (diathesis), which may then be
activated under certain environmental events such as stress.
Examples include blood-injury-injection phobia and alcoholism.
The diathesis or vulnerability does not necessarily lead to a
disorder unless some specific life event occurs.
b. A person with a large diathesis would, according to this model,
require a smaller amount of stress for a disorder to develop
compared to someone with a relatively smaller diathesis to
3. The Reciprocal gene-environment model
a. This model states that persons are believed to have a
genetically determined tendency to create the very
environmental risk factors that trigger genetic vulnerabilities.
b. Such a model may be used to explain depression, divorce, and
personality characteristics such as impulsivity.
4. Nongenomic "inheritance" of behavior
a. Related to research suggesting that there has been an
overemphasis on the role of genetic influence on personality,
temperament, and their contribution to the development of
psychological disorders. Examples include research on
genetically identical mice (including rats and rhesus monkeys
using cross fostering strategies) reared in identical
environments, but perform and behave quite differently on
several experimental tasks above what genes would suggest.
b. The moral is that it is even too simplistic to say that the genetic
contributions to personality traits or psychopathology is 50%;
one must consider the heritable contribution in the context of
an individual’s past and present environment. Chapter Two – page 3
III. Neuroscience and its Contributions to Psychopathology
A. The field of neuroscience focuses on understanding the role of the nervous
system in disease and behavior. Knowing how the nervous system and
particularly the brain works is central to understanding behavior, emotion,
and cognitive processes.
B. The central nervous system (CNS)
1. Consists of the brain and spinal cord and processes all information
received from our sense organs and reacts as necessary.
2. Neurons control every thought and action, the brain contains an
average of 140 billion neurons. (Worksheet)
a. The typical neuron contains a central cell body with two
different kinds of branches. One set of branches, dendrites,
extend from the cell body to receive chemical messages from
other nerve cells which are converted into electrical impulses.
The other branch, the axon, transmits these impulses to other
neurons. Any one nerve cell is linked with multiple others.
b. Neurons themselves operate electrically, but communicate with
other neurons chemically. The synaptic cleft (or gap) is a
small space that exists between the axon of one neuron and
the dendrites of another. It is here where neurons communicate
with one another via release of neurotransmitters.
c. Neurotransmitters (page 42) are the chemicals released from
one nerve cell to another across the synaptic cleft. After a
neurotransmitter is released it is quickly drawn back from the
synaptic cleft into the same neuron via a process known as
reuptake. Major neurotransmitters implicated in
psychopathology include norepinephrine (or noradrenaline),
serotonin, dopamine, and gamma aminobutyric acid
(Brain worksheet) Chapter Two – page 4
3. The brain is divided into two parts. The lower brain stem is the most
primitive part and is responsible for most of the automatic functions
necessary for survival (e.g., breathing, sleeping, moving). The more
advanced brain systems are located in the forebrain.
a. The hindbrain is the lowest part of the brainstem, and
contains the medulla, pons, and cerebellum (motor
coordination). These structures control activities such as
breathing, heartbeat, and digestion.
b. The midbrain coordinates movement with sensory input and
contains parts of the reticular activating system (RAS). The RAS
contributes to arousal, tension, and waking and sleeping.
c. At the very top of the brain stem (i.e., above the hindbrain) lies
the diencephalon, which contains the thalamus and
hypothalamus; these structures help transmit information to
the forebrain and are integral to behavior and emotion.
d. At the very base of the forebrain (just above the thalamus and
hypothalamus) is the telencephalon, containing the limbic
system. Limbic means "border," and this system figures
prominently in much of psychopathology. It includes the
following structures: hippocampus (sea horse), cingulate
gyrus (girdle), septum (partition), and amygdala
(almond). Emotional expression, impulse control, sex,
aggression, hunger, and thirst are controlled by this part of the
brain. Another area at the base of the forebrain is the basal
ganglia, including the caudate (tailed) nucleus. Motor
behavior is controlled by this area, and damage can cause
twitching or shaking.
e. The largest part of the forebrain is the cerebral cortex which
contains over 80% of the neurons in the CNS. Reasoning and
creative skills are derived from this brain area. The cerebral
cortex is divided into two near-symmetrical hemispheres: the
left hemisphere appears to be responsible for verbal and
cognitive processes, whereas the right hemisphere appears
more responsible for spatial abilities.
f. Each hemisphere of the cerebral cortex consists of four
separate areas of lobes. The temporal lobe is associated with
the recognition of sights and sounds and long-term memory
storage. The parietal lobe is associated with touch
recognition. The occipital lobe integrates visual input. The
frontal lobe is most interesting from the standpoint of
psychopathology and is largely responsible for thinking and
reasoning abilities, memory; it enables one to relate to people
and events in the world and to behave as social animals. Chapter Two – page 5
C. The peripheral nervous system works in coordination with the brain stem
to ensure proper bodily functioning and consists of the (1) somatic nervous
system, which controls muscles and movement, and (2) autonomic
nervous system (ANS), which is divided into the sympathetic and
parasympathetic nervous systems. The ANS regulates the cardiovascular
system, endocrine system (e.g., pituitary, adrenal, thyroid, gonadal glands)
and aids in digestion and regulation of body temperature.
1. The sympathetic and parasympathetic branches of the ANS operate in
a complementary fashion. The sympathetic nervous system mobilizes
the body (e.g., increases heart rate) during periods of stress or danger
and is part of the emergency or alarm response; the
parasympathetic nervous system renormalizes arousal and facilitates
2. The endocrine system produces its own chemical messengers (i.e.,
hormones) and releases them directly into the bloodstream. Adrenal
glands produce epinephrine (also called adrenaline) in response to
stress, including salt-regulating hormones; the thyroid produces
thyroxine, which facilitates energy metabolism and growth; the
pituitary is the master gland that produces several regulatory
hormones; and the gonads produce sex hormones (e.g., testosterone
and estrogen). The endocrine system is closely related to the immune
system and is implicated in anxiety, stress-related, and sexual
3. The hypothalamic-pituitary-adrenalcortical axis (HYPAC axis)
illustrates the connection between the nervous and endocrine systems
and is implicated in several forms of psychopathology.
1. Drug therapies function by either increasing or decreasing the flow of
specific neurotransmitters. Agonists increase the activity of a
neurotransmitter by mimicking its effects. Some drugs, known as
antagonists, function to inhibit or block the production of
neurotransmitter or function indirectly to prevent the chemical from
reaching the next neuron by closing or occupying the receptors; other
drugs increase production of competing biochemicals that deactivate
the neurotransmitter or produce effects opposite those produced by
the neurotransmitter (inverse agonists). Most drugs are either
agnostic or antagonistic.
2. Types of neurotransmitters include:
a. Serotonin (5HT) is concentrated in the midbrain and
connected to the cortex, thus producing widespread effects on
behavior, mood, and thought processes. Extremely low levels of
serotonin are associated with less inhibition, instability,
impulsivity, and tendencies to overreact to situations (e.g.,
aggression, suicide, impulsive overeating, excessive sexual
behavior. Tricyclic antidepressants (e.g., imipramine), and new
classes of serotonin specific reuptake inhibitors (SSRIs; e.g.,
Prozac) affect the serotonergic system (see also St. John’s-
wort). Chapter Two – page 6